Sometimes I get the question,
“Is there a benefit to using spray foam on the inside of a metal building when we know it will not be conditioned?”
Obviously when a building is going to be conditioned – heated in the winter or air conditioning in the summer – that’s where the energy efficiency discussion comes into play, that’s where the owners are paying for the operation of the building, they’re paying for comfort inside the structure for whatever the operational purposes of the structure, they’re paying a monthly bill, and oftentimes when we talk about insulation, that’s our expectation, that we are cutting down a monthly expense and providing some form of savings to the customer.
However, energy savings is often not the key reason that owners decide to buy; savings sounds good and it may seem like a lot of your buyers are buying because of energy savings but often times savings alone is not why they’re buying.
With an unconditioned metal building they are not going to get any energy savings, so there will be no monetary savings on a month-to-month basis, so what’s the benefit?
Well, it all comes down to comfort, it’s all a comfort situation.
So, if it’s a 100F degrees outside in the south the metal building skin could easily be a 150F degrees.
As the heat from that metal skin radiates to the inside of that building, the temperature inside the building can start to escalate throughout the day.
If it’s a workshop of some kind or a big agricultural building that’s going to be used for rodeos or dog shows or some other group event, the comfort of the attendees and participants can be critical.
The operators will likely have bay doors open on a regular basis and use fans to move air around the building to offer some type of comfort, but they are not going to condition these structures very effectively.
By insulating the inside of these buildings with spray foam insulation, they are going to create a radiant break on the inside of the building, so when that 150-degree metal stays hot during the day, even after the sun has gone down, the interior radiant surface is not the interior face of the metal, it is now the interior face of the spray foam insulation.
Now, the interior face of the spray foam insulation is going to be closer to the ambient air temperature so it’s still going to be around a 100-degrees during the hottest part of the day in the south, close to the exterior air temperature.
But if there was no radiant break on the inside of the metal, the radiant heat would come off the metal and it would heat the interior space and you would get a hotter environment inside the building, and in some situations the interior environment could be hotter indoors than the temperature outdoors.
This phenomenon happens in traditional attics when the radiant load coming off the roof deck heats the attic space and makes the attic temperature hotter than the exterior temperature.
This radiant concept happens in attics, it happens in metal buildings, it happens in workshops, it happens in all types of structures that have no consistent conditioning, where a radiant load can build up and some of that energy is radiated to the surrounding air on the inside of that space.
So that’s just a tip to keep in mind.
When you are working with an owner of an unconditioned structure, savings obviously is not a pertinent topic, but comfort for the occupants is going to be more relevant.
Occupant comfort could be important in many different situations:
- Guests in an arena for a rodeo, farm show, or agricultural show
- Guests and exhibitors in a convention building
- Workers in an agricultural building, like an animal barn or vegetable storage
- Animals in a barn, like chicken coop or a dairy farm
Studies have shown that workers and producing farm animals are higher performing and get more work done if the environment they operate in is comfortable. These are some of the reasons that an owner would choose to insulate a building even though there is no air conditioning or heating applied to the structure.
